The present invention generally relates to the field of manufacture and assembly of circuit boards. More specifically it relates to a method and means for exposing components contained in compartments in a carrier tape and covered by a cover tape, including releasing and lifting of a lateral portion of the cover tape from the carrier tape.
Generally, within the field of manufacture and assembly of circuit boards, electronic components are fed to a component mounting machine for mechanically and/or electrically mounting the components onto circuit boards. These surface mounted components are often delivered spaced apart along the length of a component tape, which consists of a lower carrier tape provided with compartments, one for each component, and an upper cover, or cover tape or protective tape. After positioning the electronic components in the corresponding compartments, the cover tape is attached to the carrier tape, and the component tape is wound on a component reel. The attachment of the cover tape to the carrier tape can, for instance be performed by providing either the cover tape or the carrier tape with adhesive areas, or by fusing the cover tape to the carrier tape.
When mounting the components on the circuit board, a component reel is positioned at a component mounting machine and the component tape is fed to the machine via a tape guide, where the cover tape is released and lifted from the carrier tape at a lateral portion, so as to expose each component in a picking position where it can be picked up and mounted on the circuit board.
The tape guide, where the components are exposed, can optionally be integrated with a complete feeding device, including a tape magazine and a feeding mechanism.
However, the tape guide can also be of a kind disclosed in WO 00/38491 which is incorporated hereby by reference. The tape guide disclosed in this-document is in the form of an adapter with the ability to perform loading and/or unloading of a component tape into and from the tape guide, remote from the component mounting machine. The component tape reel and the tape guide can thus be easily and quickly releasable mounted to the component mounting machine.
For separating the cover tape from the carrier tape, the separating means, according to WO 00/38491, is provided with a tip portion. Said tip portion protrudes backwards against the feeding direction of the component tape and is located between the carrier tape and the cover tape in the region above the compartments in the carrier tape. The tip portion of the separating means is formed with a wing portion, which extends in an oblique angle in the direction forward/sideways in relation to the feeding direction, toward the side of the component tape where the cover is being released from the carrier tape. On each side of the component tape, there is a tape guiding wall of which the separating means is attached to the tape guiding wall on the same side as the cover tape is being released. When feeding the component tape forward, the wing portion accordingly will split and release the cover tape from the carrier tape at one side of the compartments in the carrier tape.
From the releasing position at the wing portion, the lifting of the carrier tape by folding it along the unreleased portion, must be performed over an extended length until the compartments are fully exposed and access is made to the components. For this reason the separating means is combined with a cover means, ranging from the tip portion to the picking position, in close proximity to the upper surface of the carrier tape. The cover means prevents components from escaping from the compartments due to vibrations and the like, until they have reached the picking position. To enhance the bearing contact between the carrier tape and the cover means, the tape guide preferably is provided with a spring actuated contact means which bear against a lower surface of the carrier tape, pressing it against the cover means.
However, during operation with a tape guide according to WO 00/38491, it has been experienced that the friction between the component tape and the cover tape sometimes is so high that the feeding mechanism is not capable of feeding the component tape through the tape guide. It has also occurred that components have escaped from the compartments in the region between the tip portion and the picking position, though the contact means is pressing the carrier tape against the cover means. However, it is not an option available to enhance the pressing force further to ensure proper contact between the carrier tape and the cover means, since this also would increase the friction further.
It is an object of the invention to provide a solution to the problems and drawbacks experienced in the prior art, in form of high friction and components escaping from the carrier tape prior to reaching the picking position. This and other objects are achieved according to the present invention by providing a method and a means or device for exposing components having the features defined in the independent claims. Preferred embodiments are defined in the dependent claims.
For the purpose of clarity the term lateral refers to the lateral direction of the carrier tape. The terms backward and forward refer to the direction opposite and along the feeding direction of the carrier tape, respectively.
The present invention is based on the insight that the problems and draw-backs of the prior art emanate from the fact that debris, for example in the form of fibers and/or glue from the carrier tape, the cover tape and the adhesive therebetween, collects on the edges and surfaces of the separating means or member and the cover means or member. On one hand this causes enhanced friction since the debris on the edges and surfaces tend to slow down the feeding motion of the component tape. On the other hand the debris collected on edges that are not perpendicular but have an oblique angle in relation to the feeding direction, such as the wing portion, tend to guide and direct the debris laterally where it may be accumulated in corners, folds, yokes and the like of the separating means and cover means, into small granules or particles. These particles cause enhanced friction to the feeding motion as long as they are adhered to the separating means and cover means, but may also cause depression of the carrier tape by pressing the carrier tape downwards, especially if they come loose and follow the carrier tape during feeding in the region between the carrier tape and the separating/cover means . Such depression causes a clearance between the carrier tape and the separating/cover means through which components may escape.
According to the invention, the objects are achieved by avoiding accumulation of the debris in any corners, folds, yokes and the like, but instead effect continuous guiding and discharging of the debris. In the preferred embodiment this is performed in the lateral direction, such that the debris may fall out beyond the outer periphery of the carrier tape, or in the feeding direction, such that it follows the feeding motion of the tape through clearances between the separating/cover means.
According to a preferred embodiment of the invention, the wing portion is extended in the lateral direction, such that it reaches beyond the lateral edge of the component tape. This assures that released debris is guided by the wing portion in lateral direction for discharging outside of the carrier tape. The tape guide according to the preferred embodiment is of a kind where the component tape is guided between two opposed, vertical wall elements. To allow debris to be discharged outside of the tape guide, and not being accumulated inside of the same, the wall element on the release side of the component tape, i.e. the same side as the wing portion, is formed with an opening in the region where the lateral portion of the oblique angled edge of the wing portion meets the wall element, through which debris may escape. It would however be possible to let the wing portion be terminated above the carrier tape before it reaches beyond the lateral edge of the tape, under condition that measures are taken downstream of the wing portion so that debris left on the carrier tape do not accumulate, and under condition of course that the wing portion is capable of releasing the cover tape completely along one side. Since the cover tape often is adhered along a narrow path on each side of the compartments, this would be possible even though the wing portion does not reach beyond the lateral edge of the carrier tape.
In the preferred embodiment there is also arranged a clearance in form of a passage or channel in or immediately lateral from a surface of the cover means. The channel is directed along the feeding direction and is positioned in the region where the separating and cover means is attached to the wall element. In the attachment area between the separating and cover means and the wall element, a corner or yoke is formed in a portion rearmost against the feeding direction. This spot is a place where debris may accumulate. By arranging the channel, according to the invention, this risk is eliminated such that when released debris, for instance by the tip portion, is guided towards the corner, it can continuously and without accumulating be transferred via the channel through the tape guide.
The channel is located in a region outside the compartments in the carrier tape and preferably the channel coincides with the narrow path where the cover tape has been attached to the carrier tape. This is favorable since possible residues from glue may cause accumulation of particles and increased friction if it is transferred through the tape guide in contact with the cover means.
One way in which the debris is formed is when edges of the separating and cover means that are faced backwards against the feeding direction, scrape against the upper surface of the carrier tape. For this reason it is preferred, according to the invention, that clearances are provided such that edges that are not parallel to the feeding direction is formed with an upwardly bent edge portion, such that said edge do not bear and scrape against the carrier tape.
It is clear that the invention can be carried out in many different ways within the scope of the following claims. The preferred embodiment of the invention is provided with a combination of all the facilities described above. However, it should be understood that other embodiments can have just one or a few of these facilities in any combination, or even facilities not mentioned here for discharging of debris from the tape guide, without departing from the scope of the invention. In the hereafter described, preferred embodiment, the exposure means or device is integrated into one unit. However, it would also be possible to let, for instance the separating means and the cover means, be separate units which are combined.
Further details and aspects of the invention will become apparent from the following detailed description of embodiments of the invention, reference being made to the accompanying drawings, wherein like reference numerals refer to similar parts throughout.